The invention relates to a ticket printer, in particular for tickets of paper or cardboard or of material that is similar to paper or cardboard.
In particular, reference is made to a ticket printer provided with a system that is able to detect the absence of the support (paper or cardboard) on which to print.
Specifically, but not exclusively, the invention can be used for printing on a support formed by a continuous strip (for example of paper or cardboard) having in set zones holes or notches, such as, for example holes or notches obtained by die-cutting.
The prior art already comprises ticket printers, such as, for example, those shown in patent publications U.S. Pat. No. 6,929,417 and JP 2002361959.
Ticket printers are known in which a sensor (end of paper sensor) sends a signal indicating the presence or absence of the printing support (paper or cardboard). The signal is in general used by the control unit of the printer to avoid printing in the absence of the printing support and/or to indicate the need for a new supply of printing support.
One known presence or end of paper sensor comprises an optic sensor having a signal emitter and receiver arranged on the two opposite sides of a paper path along which the paper is moved by a dragging device. The presence of the paper hinders reception of the emitted optic signal whereas in the absence of paper the emitted signal can be received.
Another known presence or end of paper sensor comprises a reflective optic sensor having a signal emitter and receiver arranged on the same side of the paper path, so in presence of paper the emitted signal can be received through the effect of the reflection on the paper, whereas in the absence of paper the emitted signal is not received because it is not reflected.
If a continuous strip of paper with holes or notches is supplied along the paper path there is the risk of a false end of paper signal due to the transit of a gap (hole or notch) in the detecting zone in which the optic sensor operates.
Another problem, which is typical of reflection sensors, is the risk of a false end of paper signal due to the transit of an area that is black in colour (or has low reflective capacity) of the paper in the detecting zone in which the optic sensor operates.
US 2006/0227200 describes a printer as in the preamble of claim 1.